<!DOCTYPE html>
<html>
<head>
    <title>Interval Example</title>
</head>
<body>
    <script type="text/javascript">

        //avoid!
        setInterval("alert('Hello world!') ", 10000);
        
        //preferred
        setInterval(function() { 
            alert("Hello world!"); 
        }, 10000);            


    </script>
</body>
</html>
